Modelling adsorption rate in a rotating bed reactor

Abstract: SpinChem AB designs rotating bed reactors (RBR:s) that are used to conduct reactions between solid and liquid phase. In this work a model have been developed that predicts the performance of the S2 RBR. Coupled with simulations the model could be used to improve current and future RBR designs.  The model predicts the reaction rate inside the RBR during a de-colourization process where methylene blue was adsorped onto an adsorbent that was chosen during a screening study. The materials investigated were XAD1600N, MN102, activated carbon and IRN99 where the suitability of a material was judged upon the capacity and reproducibility of the process, and the reaction rate dependency on the mass transport. The DOE software MODDE Pro was used to design a parameter study that produced a function that describes the reaction rate of the process as a function of the RPM of the RBR and the temperature, pH and initial concentration of the methylene blue solution. Using simulations in ANSYS Fluent and modelling the function was then converted to the final model. It was then tested by comparing experimental results with simulations of the de-colourization process where the reaction rate inside the RBR was set using the model. IRN99 was chosen as the adsorbent of the process as its capacity was the highest of the four materials studied and its reaction rate displayed a sufficient mass transport dependence. The parameter study produced a function with a high R2, Q2 and reproducibility (>0.85) but displayed a low model validity (-0.2) as a result of the noise in the experimental data. The final model agrees well with the experimental results in the whole parameter space of experiments conducted. The model is meant to be a general model that could be applied to other RBR sizes. It could therefore be used to investigate the performance of new RBR models before they are built or improve current RBR:s. Other geometries has however not been tested during this work and therefore not much can be said about its accuracy when used in this way.